Respostas

2013-08-13T10:03:57-03:00
X +  x^{2} = 90
X^2 + X = 90
X = -1 +-  \sqrt 1 - 4 * (-90) / 2
X = -1 +- 19 / 2
X = -20/2 = -10 e
X = 18/2= 9